Hv1 proton channels differentially regulate the pH of neutrophil and macrophage phagosomes by sustaining the production of phagosomal ROS that inhibit the delivery of vacuolar ATPases

Journal of Leukocyte Biology: An Official Publication of the Reticuloendothelial Society

关键词: Hvcn1;    granulocytes;    proton pump;    gp91phox ;    MPO;    phagosomal acidity;   

DOI  :  10.1189/jlb.0513251

学科分类：生理学

来源: Federation of American Societies for Experimental Biology

【 摘 要 】

ProductionofROSandmaintenanceofanappropriatepHwithinthelumenofneutrophilandmacrophagephagosomesareimportantforaneffectiveimmuneresponse.Hv1protonchannelssustainROSproductionattheplasmamembrane,buttheirroleinphagosomesisnotknown.Here,wetestedwhetherHv1channelsregulatethepHpandsustainphagosomalROSproductioninneutrophilsandmacrophages.ThepresenceofHv1channelsonphagosomesofhumanneutrophilsandmousemacrophageswasconfirmedbyWesternblotandimmunostaining.PhagosomalROSproduction,measuredwithOxyBurst‐coupledtargets,wasreducedinneutrophilsandmacrophagesisolatedfromHv1‐deficientmice.RatiometricimagingofFITC‐coupledtargetsshowedthatphagosomesacidifiedmoreslowlyinHv1‐deficientmacrophagesandtransientlyalkalinizedwhentheV‐ATPasewasinhibited.InWTneutrophils,97%ofphagosomesremainedneutral30minafterparticleingestion,whereas37%ofHv1‐deficientphagosomeswerealkaline(pH>8.3)and14%acidic(pH<6.3).ThesubpopulationofacidicphagosomeswaseliminatedbyV‐ATPaseinhibition,whereasNOXinhibitioncausedarapidacidification,independentlyofHv1expression.Finally,V‐ATPaseaccumulationonphagosomeswasinverselycorrelatedtointraphagosomalROSproductioninneutrophils.ThesedataindicatethatHvcn1ablationderegulatesneutrophilpHp,leadingtoalkalinizationinphagosomeswithresidualROSproductionortotheearlyaccumulationofV‐ATPaseonphagosomesthatfailtomountanoxidativeresponse.Hv1channelsthereforedifferentiallyregulatethepHpinneutrophilsandmacrophages,sustainingrapidacidificationinmacrophagephagosomesandmaintaininganeutralpHinneutrophilphagosomes...

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